Originally Posted by CliffordK

Looking at that center seam, I'd have to think you have less than 500 miles on that tire, although the front does wear slower than the rear. You have a couple thousand miles left to go.

I'd ride those until that center tread chevron goes away, or you start getting excessive flats, or both.

Many "road" tires start with a lot less tread than that, or some are perfectly smooth. For example, look at the "thickslick tires".

I'm still hoping to grind some tires down until either I see threads, or the tread changes color. But, I seem to give up on the tires before that point.